[patch, documentation] Document -floop-flatten as experimental

[Richard Guenther]

On Tue, Feb 28, 2012 at 9:25 AM, Thomas Koenig <tkoenig@netcologne.de> wrote:
> Hello world,
>
> the attached patch documents -floop-flatten as unsafe (see the PR).
> Tested with 'make dvi', 'make info' and 'make pdf'.  I'd like to
> get this into the 4.7 release.
>
> OK for trunk?

I have modified your patch as follows and committed it.

Richard.

2012-02-28  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR tree-optimization/53207
        * doc/invoke.texi: Document as experimental and relying on graphite.

Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 184617)
+++ gcc/doc/invoke.texi (working copy)
@@ -7289,8 +7289,12 @@ dead code elimination in loops.
 @item -floop-flatten
 @opindex floop-flatten
 Removes the loop nesting structure: transforms the loop nest into a
-single loop.  This transformation can be useful to vectorize all the
-levels of the loop nest.
+single loop.  This transformation can be useful as an enablement
+transform for vectorization and parallelization.  This feature
+is experimental.
+To use this code transformation, GCC has to be configured
+with @option{--with-ppl} and @option{--with-cloog} to enable the
+Graphite loop transformation infrastructure.

 @item -floop-parallelize-all